Snap action, push button electric switch



June 1, 1965 P|ERE 3,187,133 SNAP ACTION, PUSH BUTTON ELECTRIC SWITCHFiled March 7, 1963 3 1' Z. 2. M 5 I [/1 /I///[/ fl I 59 M 33 56 1 1 M70 Z8\ 7\ M 20 .1 -54 I 1 o 56 55 45 9 z; 64 53 I j .55

p 6/ 62 a s I 2 3 A j 67 d N .24 [c/Iw'n E P/erce,

V8 INVENTOR. 60 2'6 WM 8 McMAN/GAL Af/orn c for lip 11:00 23 UnitedStates Patent 3,187,133 SNAP ACTION, PUSH BUTTON ELECTRIC SWiTCH EdwinF. Pierce, Pasadena, Calif., assignor to Schulz Tool and ManufacturingCo., San Gabriel, Califi, a corporation of California Filed Mar. 7,1963, Ser. No. 263,497 12 Claims. (Cl. 2tlll77) This invention relatesgenerally to electromechanical devices and particularly relates to apush button switch having a snap action to provide sudden opening orclosing movements of the switch.

In a conventional push button switch, opening or closing of the contactsof the switch takes place at a speed depending upon the operator of thepush button. Accordingly, when the contacts are slowly closed, there usually occurs arcing between the contacts before they are actually incontact with each other. The danger of arcing is particularly great whenthe switch is operated at relatively high voltages. Thus, a push buttonswitch which has a snap action is desirable to minimize arcing. Inaddition, in a snap action switch, the switches are opened and closedalways at the same rate. Thus, arcing and noise are both minimized.

The switch of the present invention is of the sliding contact type. Inany sliding contact switch, the contact pressure is of great importance.If the contact pressure is too low the switch contacts may bounce thuscausing both arcing and noise or erratic signals. The arcing in due timewill corrode the contacts and thus reduce the life of the switch. On theother hand, if the contact pressure is made too high, metal particlesare worn off the contacts which are subsequently deposited on theinsulating portion of the switch which causes what is known as tracking.Accordingly, a circuit path is provided between the contacts even whenthey are in their open position.

It is accordingly an object of the present invention to provide a snapaction, push button switch which minimizes arcing and which has notracking problem.

Another object of the present invention is to provide a push buttonswitch where the speed With which the contacts are opened and closed isindependent of the operator and remains the same regardless of how fastor slow the push button is depressed or released.

A further object of the present invention is to provide a push buttonswitch of the snap action type which is provided with an insulatinglubricant thereby to minimize tracking and which has a long useful life.

Still another object of the present invention is to provide a pushbutton switch of the type referred to which will operate at relativelyhigh voltages and which will carry a relatively large wattage withoutdanger of arcing.

Still a further object of the present invention is to provide a snapaction, push button switch which can be readily designed to providebreak-before-make operation as Well as make-before-break operation.

A snap action, push button switch in accordance with the presentinvention comprises a push button which is adapted to be depressed froma normal to an actuated position. First spring means are provided forurging the push button into its normal position. There are furtherprovided cam means movable from a normal to an actuated position andback again. The cam means has two inclined surfaces projecting towardand disposed adjacent the push button. A cam follower is slidablydisposed in the push button and second spring means urge the camfollower against the inclined surfaces of the cam means.

As a result, when the push button is depressed, the cam follower willride over one of the inclined surfaces of the cam means thereby to forcethe cam means to move suddenly in a direction opposite the direction ofmovement of the push button. When the push button is 3,l87,l33 PatentedJune 1, 1965 released again the cam means will return just as suddenlyto its original position because its cam follower will again ride overthe inclined surfaces of the cam means.

A movable carrier is secured to the cam means and moves therewith. Twobrushes are fixedly disposed about the carrier and are in contact withthe carrier. A contact member has portions so disposed as to beengageable with both of the brushes in one position of the carrier andas to be disengaged from at least one of the brushes in the otherposition of the carrier.

Finally, an insulating lubricant is provided on the brushes and thecontact member. The insulating lubricant preferably has a highdielectric constant and serves the purpose to embed particles worn oilthe brushes and the contact member so that they are insulated from eachother. This in turn will prevent tracking because the embedded particlesfrom the brushes and the contact member cannot be plated out on theinsulating surface of the carrier.

The novel features that are considered characteristic of this inventionare set forth with particularity in the ap pended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional obiects and advantages thereof, will best beunderstood from the following description when read in connection withthe accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a snap action, push buttonswitch embodying the present invention;

FIG. 2 is a longitudinal sectional view taken substantially on line 22of FIG. 1;

FIG. 3 is a cross sectional View of the push button. of the inventiontaken substantially on line 33 of FIG. 2; and

FIG. 4 is a circuit diagram of the single-pole, doublethrow switchprovided by the structure of FIGS. 1 through 3.

Referring now particularly to FIGS. 1 through 3, there is illustrated asnap action, push button switch embodying the present invention. Theswitch of FIGS. 1 through 3 includes essentially a main housing 19having a circular cross section as clearly shown in FIG. 3, an end platell, a push button 12, extending opposite from the end plate 11 and areturn spring 13 disposed between the end plate 11 and the push button.The snap action, push button switch further includes a contact carrier14 movably disposed in the housing lit and preferably being formedintegral with two cams l5 and to, two telescoping cam follower members1'7 and 13 which are outwardly urged by a spring 2 3, threespring-biased brushes 21, 22 and 23 and a corresponding set of threecontacts 24, 25 and 26. Finally, the switch includes a threaded sleeve27 and three terminal lugs 28 extending through the end plate 11. Thehousing lit near one of its ends is provided with an annular recess 3%)into which extends a similar cylindrical projection 31 of the end plate11. As a result the end plate 11 closes or seals .one end of the housing19. The end plate 11 which is of generally disc shape is provided with acentral cylindrical recess 32 for receiving the return spring 13. Theother end of the housing 10 is provided with a disc 33 having a centralaperture 34 through which the push button 12 extends and is adapted toslide. The housing 10 is further provided with an outer disc 35 forreceiving the sleeve 27 provided'with outer threads 35. An annularrecess 37 is formed between the two discs 33 and 35 of the housing intowhich projects a disc 33 of the sleeve 27. The threaded sleeve 27 servesthe purpose of securing the push button switch of the invention to apanel which may be fastened to the sleeve 27 by a pair of lock nuts, notshown.

The housing 10 is further provided with two stop walls All and 41. Eachof the walls 40 and 41 is of generally disc shape and has a centralopening 42 and 43 respective- 2 1y to permit the push button straight atright angles as illustrated in FIG. 3.

explained hereinafter.

1210 pass therethrough. The purpose of the two stop walls 40 and 41 isto limit movement of the cam carrier 14 in both directions. Finally,the'housing is provided with three spaced receptacles 44 for receivingthe three brushes 21, 22 and 23. Thus, the three brushes-are fixedlydisposed on the housing 10 with respect to the movable carrier 14. e 1

. The push button 12 has an outer cylindrical portion 45 and an innerportion 46 of elongated or rectangular cross section as clearly shown inFIG. 2. The cylindrical portion 45 of the push button slides through thethreaded sleeve 27 and the housing wall 33. The inner end of the pushbutton 12 has a cylindrical recess 47 for receiving the return spring 13which urges the push button into its normal position. The enlargedportion 46 of the push button 12 also has a rectangular opening 48extending therethrough. The two [cam followers 17 and 18 are slidablydisposed in the rectangular opening 48 which forms a bearing surface forthe outer cam follower 18. y The two cam followers 17 and 18 are hollowand of substantially rectangular cross section as clearly shown inFIG. 1. The spring 20 is disposed inside the two telescoping camfollowers 17 and 18 and bears against their I respective fiat bottomsurfaces and 51. The outer surfaces 52 and 53 of the two telescoping camfollowers 17 and 18 are outwardly curved as shown in FIG. 2 but Thesesurfaces 52 and 53 bear respectively against the surfaces of the twocams 15 and 16. Each of the two cam followers 17 and 18 is provided witha plurality of apertures 54 to' permit an to enter and leave the closedspaces formed between the two cam followers. As pointed out before, the

formed in the enlarged portion 46 of the pushbuttonlZ. The inner camfollower. 17 slides within theouter cam follower 18 and has an enlargedend portion 49 which also contacts the bearing surfaces 48 of the pushbutton.

' The two cam followers 17 and 18 cooperate with the two cams 15'and 16respectively which are preferably made integral with. the movablecarrier 14, Thus, the cam 15 has two inclined cam'surfaces 5-5 and 56which are. preferably plane surfaces and which project toward'camfollower 18" slides along the bearing surfaces 48 three receptacles44 of the housing 10. The three brushes are symmetrically disposed aboutthe carrier 14 as clearly 7 shown in FIG. 3 and either contact theircooperating contact portions or are out of contact therewith dependingupon the position of the switch. Each of the brushes 1S urged by aspring 61 which is preferably a coil spring against the respectivesurfaces 57, 58 and '60 of the carrier. 7 Each of the brushes 21 to23preferably consists of a piece of sheet metal which generally is ofU-shape as clearly shown in FIGS. 1 and 2 and has a centralsubstantially rectangular projection 62 which is in. contact either withthe contact portions 24 through 26 or with the carrier surfaces 57, 5 8and 60 as the case may be. The twoouter end portions of each of theU-shaped brushes may be bent inwardly so. that the brush does not havesharp corners.

Each of the three brushes 21, 22 and 23 is electrically connected withone of the terminal lugs 28. To this end, there may be. provided aconductor 64 which may be connected to each brush such as 21 by weldingor soldering or "the like and which has its other end similarlyconnected to one of the terminal lugs 28. The terminal lugs maybeprovided with an opening 65 for connecting there- 1 to a wire orconductor by welding, soldering or the like.

The conductor 64' extends through suitable openings in the receptacles44- as clearly shown in FIGS. 1 and 2. The connections between theconductors 64 and'the respective brushes are such that each brush ispermitted to move slightly under the influence of its bias spring 61.

As clearly shown in FIG. 3, the main housing 3 may the switch arepreferably made will now be explained.

The main housing 10 maybe made from a suitable insulating material whichmay be a plastic material such diphenyl propane".

the enlarged portion 46 of the push button 12. The two Cams 15 and 16are disposed in a plane whichjintersects the push button and hence theyare oppositely arranged with their cam surfaces and 56 facing eachother.

These flat cam surfaces 55 and 56 of the two cams 15 and 16 incooperation with the two cam followers 17, 18 cause the snap action ofthe switch aswill be more fully Q The cam or contact carrier 14 as shownparticularly in FIG. 3 forms substantially a triangular prism havingthree fiat surfaces 57, 58 and 60. The three brushes 21, 22 and 23 areeach disposed in contact. with one of the respective flat surfaces 57,58 and 60 of the carrier 14. Thethree surfaces 57, 58 and 6 0 of thecarrier 14 are preferably so arranged that the pressures exerted by thethree brushes 21 to23 are at least partially balanced. As

Acontinuous contact member forming the contact porfor example as apolycarbonate. A polycarbonate is a polymer derived frorn biphenol A or4, 4 dihydroxy This compound has the chemical formula Such apolycarbonate is sold in the trade under the name of Lexan by GeneralElectric Company. This plastic material may readily be molded and can becheaply made in mass production. It is also characterized by greatimpact strength. l

The two housingportions 66 and 67 may be joined togetherby a suitablecement, by heat sealing or in any 7 other expedient manner. Lexanpermits to jointhe two housing portions by applying asolvent to thesurfaces to be joined. The two housing portions may'then be put togetherand are joined when the solvent dries.

Preferably, the push button 12, the two cam followers 17 and 1,8, thecarrier 14 as well as the two cams 15 and 16 are also made from Lexan.However, it is also possible to make the two cams 15 and 16 from amaterial tions 24, 25 and 26, is disposed in the carrier 14 in such amanner that its outer surface is flush with the surfaces 57', 58 and 60of the armature. The three contact portions 24, 25. and 26 cooperaterespectively with the three brushes 21, 22 and 23 in order to open} orclose electric circuits. Thus, the arrangement preferably is such thatone ofthe'contactportions such'as 25 is in contact with its associatedbrush 22 in the normal or nonactuated position of the switch. At thesame time the contact portion 24 is out of contact with its-brush 21.Preferably, the contact portion 26 is so disposed and of such a lengththat it remains in contact with its brush 23 in both the normal and theactuated position of the switch.

4 The three brushes 21 through 23 are disposed in the sold in the tradeunder the name of Nylotron GS. Nylotron GS is compounded together withnylon and a suitablelubricant such as graphite and molybdenumdisulphate. As a result, Nylotron GS is a plastic material which can be.readily molded and which is self-lubricating to reduce wear between thesurfaces 55 and 56 of the two cams and the two cam followers.

The end plate 11 is preferably made from a phenolic resin because such aresin will withstand higher temperatures than Lexan. The end plate 11must withstand the relatively high temperatures generated when aconductor is soldered through the aperture 65 of the terminal lugs 28.

The various springs such as a return spring 13, the bias spring 20 forthe two, cam followers and the three bias springs 61 for the threebrushes are preferably made from some spring material such, for example,as

beryllium copper. The conductor 64 may be made of copper while theterminal lugs 2s may be of tin-plated brass. The threaded sleeve 27 may,for example, consist of aluminum which may be anodized to resistcorrosion.

The various contact portions 24, and 25 preferably consist of a metalwhich has a pitted surface and which has a high work function tominimize arcing. Thus, preferably the contacts are made of molybdenumwhich has both of these qualifications. Where a high work func tion isnot essential, the contact portions 24 and 2% may, for example, be madeof copper or brass which is nickel plated, the nickel plating alsohaving pits or depressions in its surface. Alternatively, the variouscontacts may be plated with or made of tungsten, molybdenum or stainlesssteel which also provide a pitted surface.

The three brushes 21, 22 and 23, for example, may consist of or may beplated with an alloy known as coin silver which consists of 92% silverand 8% copper. This alloy has a flaking action under wear. However, anyother conducting material which has a flaking action may be used for thebrushes 21 through 23. Thus, the brushes may consist of an alloy knownas nickel silver which includes 81% copper and 18% nickel.Alternatively, the brushes may consist of or may be plated withpalladium, rhodium, platinum or gold. These metals have the propertythat they are resistant to chemical action and hence the contactsurfaces-tend to remain clean. They also have a flaking action whichfurther helps to maintain a clean contact surface. If the brushes areplated, it is sufiicient to plate the outer surface of the rectangu larprojection 62 of each brush.

Further, in accordance with the present invention the contact portions24 through 26 and the brushes 21 through 23 are coated or provided withan insulating lubricant. Preferably, the lubricant has a low surfacetension or high wetting action so that the lubricant is retained by thepitted surfaces of the contact portions 24 through 26.

By way of example, the insulating lubricating material which is used inaccordance with the present invention may include a major proportion ofmineral oil of the type used for high voltage transformers. This mineralor transformer oil withstands high temperatures as well as lowtemperatures and has a high dielectric constant because it is used fortransformers carrying up to 300,000 volts. This mineral oil ortransformer oil may be emulsified and may have a base of a tallow greasewhich will not carbonize out under conditions of wear. A minoraldetergent may be added to increase the wetting action or to decrease thesurface tension.

An insulating lubricant of this type is sold in the trade under N0. 871Switch Lube by Lubrication Company of America. This insulating lubricantincludes at least 93% mineral oil and is of relatively high viscosity.Thus, at 100 F., the viscosity may be 2,600 centistokes per second. Thismineral oil has a flash point of 559 F. In other words, when the oil isheated to 550 it will flash under the influence of an electric arc.Thus, the lubricant will withstanding arcing up to 550 F. It may beadded that the 871 Switch Lube shows substantially no corrosion.

One of the main purposes of the insulating lubricant is to embed orencapsulate worn 0E metal particles. During operation of the switch,metal particles are worn ofr" the contact portions 24 through 2 6 andthe brushes 21 to 23. These metal particles may plate out, for example,on the insulating surfaces 57, 53 and 6% of the carrier 14 to causeundesirable short circuits. The lubricating material should have a highdielectric constant so that individual encapsulated metal particles areelectrically insulated from each other so that they cannot cause shortcircuits. The contact pressure provided by the springs 61 of the threebrushes 21 to 23 should be high enough to break through the lubricatingfilm on the contact surfaces.

6 This construction further makes it possible to operate the push buttonswitch of the invention with a high contact pressure which may bedesirable for certain applications. In that case the wear of thecontacts and of the brushes is increased. Without the provision of suchan insulating lubricant the operating life of the switch would bedrastically reduced.

The operation of the snap action, push button switch will now beexplained.

The switch is illustrated in FIGS. 1 to 3 in its normal or unactuatedposition. It will be noted that the contact portion 25 is in contactwith its brush 22. Furthermore, the contact portion 26 is in contactwith its brush 25. On the other hand, the contact portion 24 isdisconnected from its brush 21. Hence, an electric circuit connected tothe terminal lugs connected to brushes 22 and 23 is closed. On the otherhand, an electric circuit connected between the terminal lugs of brushes21 and 23 is open.

Assuming now that the push button 12 is pressed downwardly in thedirection of arrow '70. As a result, the two surfaces 52 and 53 of thetwo cam followers 1'7 and 18 are pushed by the downward movement of thepush button against the cam surfaces 5'5 of the two cams 15 and 1%.Hence, the bias spring 26 of the two cam followers 17 and 13 isgradually compressed thus storing energy. Eventually, the surfaces 52and 53 of the cam followers pass the edge of the two cams and begin toslide down on the inclined surfaces 56 of the two cams. As a result, thetwo cams 15 and 16 are forced to move in the direction of arrow 71, thatis, against the direction of movement of the push button. In otherwords, the two cams 15 and 16 and the carrier 14 are forced to movesuddenly in the direction of arrow 71. This in turn will cause thecontact brush 22 to disengage from its contact 25 while shortlythereafter the contact brush 21 engages the contact portion 24. Brush 23remains in contact with its contact portion 26.

The switch of FlGS. 1 to 3 is a single-pole, doublethrow switch of thetype illustrated schematically in FIG. 4. In the normal or unactuatedposition, the two con tact portions 25 and 26 are closed. When the pushbutton 12 is depressed in the manner just described, the two contactportions 24 and 26 are closed thus closing the circuit between terminals2 and 3 while opening the circuit between terminals 1 and 2. It will benoted that the construction of the switch as illustrated particularly inFIG. 1 is such that contacts 25 and 26 break before contacts 24 and 2dmake. However, it will be apparent that by making either one of thecontact portions 25 or 24 somewhat longer, it is possible to obtainmake-before-break operation. I

When the push but-ton 12 is released again after it has previously beendepressed, the push button will be moved by its return spring 13 in adirection opposite that of arrow 76). A similar operation takes place aspreviously described. Thus, the surfaces 52 and 53 of the two camfollowers will initially ride over the cam surfaces 56 therebycompressing the spring 21 The spring releases again as soon as the twosurfaces 52 and 53 have been moved over the edge of the two cam surfaceswhereupon the two cam followers ride on the surfaces 55. As a result,the two cams 15 and 16 and the carrier 14 are forced to move suddenly ina direction opposite that of the arrow 71. As clearly shown in FIG. 2,the two cams 15 and 16 and the carrier 14 move between the stop walls 4%and 41 which thus limit the move- 'ment of the carrier.

It may also be noted that the carrier 14 is supported between the threebrushes 21, 22 and 23, the construction being suchthat the contactpressures are nearly balanced. If the carrier 14 could be made to havethe shape of a triangular prism with equal sides the pressures exertedby the three brushes and their springs would balance exactly.

Depending on the construction of the two cams 15 and 1 1,100,000 cycles.

suitable apertures in the end platell.

turn will minimize arcing even with relat iyely high voltages.

Thus, the snap action, push button switch of them- 'vention has beentested with a voltage of 150 volts and a With the applied current andvoltage, the switch has been direct current of 260 millianiperes or 39watts.

tested and has been found to have a useful life'of over at relativelylow voltages, for example, at 2 to 4 volts and a current of 100milliampere-s or 0.2 to 0.4 watt. As such low voltages andlowwattages,[the noise of the switch is extremely low and the switchfinds wide application in the electronic or instrumentation fields.

Due to the rapid movement'of the switch contacts While they either makeor break contact, arcing is minimized and presents no problem. On theother hand, the dielectric-grease applied between the contactingsurfaces of the contact portions 24 through 26 and of the brushes 21 to23, substantially eliminates any tracking problems even at high contactpressures. V a

It may also be noted that the speed of movement from the normal to theactuated position and back again to the normal position ofthe switch isindependent of the operator. In other words, whether the push button isdepressed rapidly or'slowly, the switch will still operate at itspredetermined speed which depends primarily on the construction of thetwo cams and the force'of the bias spring 20.

"The. switch of the invention may be assembled in the following mahner:Y

I .At first the three terminal lugs 28 are pushed through Thereafter,the three conductors 64 are soldered or welded to their terminal lugs 28and to their respective brushes 21 to 2.3.

Thereupon, the three brushes 21 through 23 with their bias springs 61are inserted into their respective receptacles 44in the main housingportions 66 and 67. Then the two cam,;followers 17 and 18 are pushedthrough the 'apertureAS inthe push button together with their Theswitchwill of course also work bias spring 20; Subsequently, the two earns 15and 16 with the carrier 14 arepushed about the enlargedportion 46 of thepush button '12 with the cam followers in position. Then the returnspring 13 is inserted into the push button 12 and into the cylindricalaperture 32 in the end plate 11. Thereupon, the threaded sleeve 27 isinserted aboutthe push button 12.

vl Finally, the two housing portions '66 and 67 are assembled about theend plate 11 and the threaded sleeve '27. The two housing portions maythen be sealed to-' gether in any manner previously explained and theswitch is ready for operation.

Instead of providing a' 'single-pole, ouble-throw switch as illustratedin the drawing it is of course feasible to provide a single-pole,single-throw switch. In other words, all that is needed are two contactbrushes and two contact elements to open and close a single electriccircuit. i i As pointed out before, the contact portion 26 preterably islong enough so that its brush 23 remains in contact therewith in boththe normal and the actuated position. Thus, it is not necessary that twobrushes simultaneouslycontact two contact portions to either open orclose'an electric circuit. simultaneously, the danger of arcing isincreased in an unpredictable manner. There has thus been disclosed animproved push button switch of the snap action type. The switch of theinvention minimizes arcing andminimizes tracking of the slidingcontacts. The switch of the invention is capable of switching relativelyhigh voltages and large wattages substantially without. arcing. Inaddition, the switch has a. life expectancy of well over a millioncycles, The rapid If both contacts are not made acceleration of theswitch mechanism'is entirely independent of the manner in which the pushbutton is actuated whether by hand or by machine. Asa result, not onlyis arcing minimized but the switch has a very low noise which issubstantially eliminated at low voltagesJ construction and arrangementof the parts of the invention without departing from the spirit andscope thereof or sacrificing its material advantages, the arrangementhereinbefore described being merely byway of example.

I do not wish to be restricted to the specific form shown or usesmentioned except as defined in the accompanying claims, wherein variousportion-s have been separated for clarity or reading and not foremphasis.

I claim: 1. A snap action, push button switch comprising:

(a) a push button adapted to be depressed from a normal to an actuatedposition; b) first spring means urging said push button into its normalposition; P (-c) cam means having two cam surfaces forming an edgeprojecting toward and disposed adjacent said' push button, said cammeans being'movable independently of the movement of said push buttonfrom a normal to an actuated position and back again; b) cam followerslid-ably disposed in said push button and movable therewith; F (e)second spring means urging said cam fol-lower against the surfaces ofsaid cam means, whereby upon depressing said push button, said oamfollower will ride over one of said surfaces to force said cam means tomove suddenly in 'a' direction opposite the direction of movement ofsaid push button, and whereby said cam means will return suddenly to itsoriginal position upon release of said push button; (f) 'a movablecarrier secured tosai-d cam means and movable therewith; j (g) twobrushes fixedly'disposed about .said carrier and in contact therewithand; 1

(l1) a contact member having portionsjdisposed' in said carrier so as tobe engageablewith both'of. said brushes in one position of said carrierand as to be dissengaged from at least "one of said .brushes'in towardand disposed adjacent said push button and movable independently of themovement, ofsaid push button from a'normal to an actuated position andback again; r v (d) a cam follower slidably disposed in said push buttonand movable therewith; (e) second spring means urging said cam follower7 against the inclined surfaces of said-cam means, whereby upondepressing sai d'push button, said cam follower will ride overone ofsaid inclined surfaces to force said cam means to move suddenly in adirection opposite the direction of movement of said push button, andwhereby said cam means will return suddenly to its original positionupon release r of said push button;

(f) a movable carrier secured to said cam movable therewith; (g) twoconductive brushes fixedly disposed about said .carrier'and in contacttherewith; and (h) a conductive contact member having portions disenemas (b) first spring means urging said push but-ton into its normalposition;

(c) cam means having two inclined surfaces projecting toward anddisposed adjacent said push button and movable from a normal to anactuated position and back again;

(d) a cam follower slida'bly disposed in said push button;

(e) second spring means urging said cam follower against the inclinedsurfaces of said cam means, whereby upon depressing said push button,said cam follower will ride over one of said inclined surfaces to forcesaid cam means to move suddenly in a direction opposite the direction ofmovement of said push button, and whereby said cam means will return suddenly to its original position upon release of said push button;

(f) a movable carrier secured to said cam means and movable therewith;

(g) two brushes fixedly disposed about said carrier and in contacttherewith, each of said brushes having a contact surface consisting of ametal having a flaking action; and

(h) a contact member having portions so disposed as to be engagcablewith both of said brushes in one position of said carrier and as to bedisengaged from at least one of said brushes in the other positionthereof, said contact member having contact surfaces consisting of ametal having a pitted surface; and

(i) an insulating lubricant provided between said brushes and contactmember for embedding and encapsulating metal particles worn off saidbrushes and said contact member, said lubni-cant having a low surfacetension so as to be retained by the pits in the surface of said contactmember.

4. A snap action, push button switch comprising:

(a) a push button adapted to be depressed from a normal to an actuatedposition;

(b) first spring means urging said push button into its normal position;

(c) cam means having two inclined surfaces projecting toward anddisposed adjacent said push button and movable from a normal to anactuated position and back again;

(d) a cam follower slidably disposed in said push bu tton;

(e) second spring means urging said cam follower against the inclinedsurfaces of said cam means, whereby upon depressing said push button,said cam follower will ride over one of said inclined surfaces to forcesaid cam means to move suddenly in a direction opposite the direction ofmovement of said push button, and whereby said cam means will returnsuddenly to its original position upon release of said push button;

(f) a movable carrier secured to said cam means and movable therewith;

(g) two brushes fixedly disposed about said carrier and in contacttherewith, each of said brushes having a contact surface consisting of ametal having a flaking action;

(h) a contact member having portions so disposed as to be engageablewith said brushes in one position of said carrier and as to bedisengaged from at least one of said brushes in the other positionthereof, said contact member having a contact surface consisting of ametal having a high work function and a pitted surface; and

(i) an insulating lubricant provided between I said brushes and contactmember for embedding and encapsulating metal particles worn ofi saidbrushes and said contact member, said lubricant having a high wettingaction so as to be retained in the pits of said contact member.

5. A snap action, push button switch comprising:

(a) a housing;

(b) a push button movably disposed in said housing and adapted to bedepressed from a normal to an actuated position;

(0) a return spring disposed between said housing and said push buttonfor urging said push button into its normal position; V

(d) a pair of cam follower members slidably disposed in said pushbutton;

(e) two cam members movably disposed in said housing in a planeintersecting said push button and adjacent thereto, each of said cammembers having two inclined surfaces projecting toward said push button;

(f) first spring means urging each of said cam follower members againstthe inclined surfaces of one of said cam members, whereby said cammembers will suddenly move upon depressing said push button in adirection opposite the direction of movement of said push button andwill suddenly return to their normal position upon release of said pushbutton;

(g) a carrier integral with said cam members and movable therewith, saidcarrier having two substantially fiat surfaces;

(h) two conductive brushes disposed in said housing and in contact withthe surfaces of said carrier;

(i) second spring means for urging each of said brushes against one ofthe surfaces of said carrier; and

(j) a conductive contact member so disposed in the surfaces of saidcarrier that both of said brushes contact said contact member when saidcarrier is in one of its positions and so that only one of said brushescontacts said contact member when said armature is in the other one ofsaid positions.

6. A snap action, push button switch comprising:

(a) a housing;

(b) a push button movably disposed in said housing and adapted to bedepressed from a normal to an actuated position;

(0) a return spring disposed between said housing and said push buttonfor urging said push button into its normal position;

(d) a pair of telescoping cam follower members slidably disposed in saidpush button; I (6) two cam members movably disposed in said housing in aplane intersecting said push button and adjacent thereto, each of saidcam members having two inclined surfaces projecting toward said pushbutton;

(f) first spring means urging each of said cam follower members againstthe inclined surfaces of one of said cam members, whereby said cammembers will suddenly move upon depressing said push button in adirection opposite the direction of movement of said push button andwill suddenly return to their normal position upon release of said pushbutton;

(g) an insulating carrier integral with said cam members and movabletherewith, said carrier having two substantially fiat surfaces;

(h) two conductive brushes disposed in said housing and in contact withthe surfaces of said carrier;

(i) second spring means for urging each of said brushes against one ofthe surfaces of said carrier; and

(j) a conductive contact member so disposed in the surfaces of saidcarrier that both of said brushes contact said contact member when saidcarrier is in .one of its positions and so that only one of said brushescontacts said contact member when said carrier is in the other one ofsaid positions.

(a) a housing;

(b) a push button movably disposed in said housing and adapted tobe'depressed from a normalto an actuated position; V

(c) a return spring disposed between said housing and said push buttonfor urging said push button into its normal position;

(d) a pair of telescoping cam follower members slidably disposedin saidpush button;

, (e) two cam members movably disposed in said housing in aplaneintersecting said push button and adjacent thereto, each of saidcam members having two inclined surfaces projectingtoward said pushbutton;

(f) first spring means urging each of said cam follower members againstthe inclined surfaces of one of said cam members, whereby said cammembers will suddenly move upon depressing said push button in adirection opposite the direction of movement of said push button andwill suddenly return to their normal position upon release of said pushbutton;

' (g) an insulating carrier integral with said cam members and'movabletherewith, said carrier having two substantially fiat surfaces;

(11) two brushes disposed in said housing, each being in contact withone of the surfaces of said carrier, each of said brushes consisting ofa substantially Uash ape'd piece of sheet metal, each brush having a Vsubstantially rectangular, central, contact-forming projection; I

(i) second spring means for urging each of said brushes against itsassociated surface of said carrier; and

I (j)' a conductive contact member so disposed in the surfaces of saidcarrier and flush therewith that both ofsaid contact-forming projectionsof said brushes contact said contact member when said carrier is in oneofitsposit ionsand so that only one of said-projections of said brushescontacts said contact member when said carrier is in the other one ofsaid positions.

8. A snap action, push button switch comprising:

(a) ahousing;

(b) a push button movably disposed in said housing and adapted to bedepressed from 'a normal to an actuated position;

(c) a return spring disposed between said housing and said pushbuttonfor urging said push button into itsnormal position; (d) a pair oftelescoping cam follower members slidably. disposed: in said pushbutton;

(g) an insulating carrier integral with-said cam mem-' bers andrnovabletherewith, said carrier having two substantially fiat surfaces;

(h) two conductive brushes disposed in said housing and each being incontact with one of the surfaces of said carrier;

V ('i) two terminal lugs extending'through said housing,

each being electrically connected to one of said brushes;

. (j) second spring means for urging each of said brushes against theassociated carrier surface; and

(k) a conductive contact member disposed flush in the surfaces of saidcarrier in such a manner that both of said brushes. contact's'aid'contact member when (0) a return spring disposed between said housingand said push button for urging said push button into its normalposition; V

(d) a carrier of insulating material slidably disposed in said housingand having three substantially flat surfaces, said housing providingthree spaced receptacles and having two spaced stop members, saidcarrier being movable between said two stop members from a normal to anactuated position;

(e) a conductive brush in each of said receptacles, said receptaclesbeing so disposed that each brush, is in contact with one of the fiatsurfaces of said carrier;

(f) first spring means urging each of said brushes against itscarriersurface; V

(g) said carrier being provided with two cams disposed in a planeintersecting said push button, eachlof said cams having two inclinedsurfaces projecting toward said push button;

(11) two telescoping cam followers slidably disposed in said push buttonand movable therewith;

(i) second spring means for urging said cam followers away from eachother and against the inclined surfaces of said two cams, whereby upondepressing said push button said cam followers will ride 'over theinclined surfaces of said cams to force said carrier to move suddenly ina direction opposite the direction of movement of said push buttonagainst one of said stop members and to force said carrier to returnsuddenly into its normal position upon releasing said push buttons; and

(j) a continuous conductive contact member extending over the flatsurfaces of said carrier and substantially flush therewith, said contactmember being so disposed that a first and second brush contact saidcontact member in the normal position of said carrier and that saidsecond and third brush contact said contact member in the actuatedposit-ion of said carrier.

10. A snap action, push-button switch comprising:

(a) a housing of insulating material; I

(b) a push button extending through one end of said housing andsubstantially closing said housing, said push button being slidable insaid housing from a normal to an actuated position and back again;

(c) atreturn spring disposed between said housing and said push buttonfor'urging said push button into its normal position;

(d) a carrier of insulating materialslidably disposed 1 1n said housingand forming substantially a, triangular prism having three substantiallyfiat surfaces, said housing providing three spacedreceptacles and havmgtwo spaced stop members, said carrier being movable between said twostop members from a normal to an actuated position; V

(e) a conductive brush in each of said receptacles, said Q away fromeach other and against the inclined surfaces of said two cams, wherebyupon depressing said push button said cam followers will ride over theinclined surfaces of said cams to force said carrier to move suddenly ina direction opposite the direction of movement of said push buttonagainst one of said stop members and to force said carrier to returnsuddenly into its normal position upon releasing said push button;

(j) a continuous conductive contact member extending over the fiatsurfaces of said carrier and substantially flush therewith, said contactmember being so disposed that a first and second brush contact saidcontact member in the normal position of said carrier and that saidsecond and third brush contact said contact member in the actuatedposition of said carrier;

(k) three terminal lugs extending through said housing; and

(l) conductors connecting each terminal lug to one of said brushes sothat electric circuits connected to said terminal lugs can be opened andclosed upon actuation of said push button.

11. A snap action, push button switch comprising:

(a) a main housing of insulating material;

(b) an end plate closing one end of said housing;

() a push button extending through the opposite end of said housing andsubstantially closing said housing, said push button being slidable insaid housing from a normal to an actuated position and back again;

(d) a return spring disposed between said housing and said push buttonfor urging said push button into its normal position;

(e) a carrier of insulating material slidably disposed in said housingand forming substantially a triangular prism having three substantiallyflat surfaces, said housing providing three spaced receptacles andhaving two spaced stop members, said carrier being movable between saidtwo stop members from -a normal to an actuated position;

(f) a conductive brush in each of said receptacles, said receptaclesbeing so disposed that each brush is in contact with one of the flatsurfaces of said carrier;

(g) first spring means urging each of said brushes against its carriersurface;

(h) said carrier being provided with two cams disposed in a planeintersecting said push button, each of said cams having two inclinedsurfaces projecting toward said push button;

(i) two telescoping cam followers slidably disposed in said push buttonand movable therewith;

(3') second spring means for urging said cam followers away from eachother and against the inclined surfaces of said two cams, whereby upondepressing said push button said cam followers will ride over theinclined surfaces of said cams to force said carrier to move suddenly ina direction opposite the direction of movement of said push buttonagainst one of said stop members and to force said carrier to returnsuddenly into its normal position upon releasing said push button;

(1;) a continuous conductive contact member extending over the fiatsurfaces of said carrier and substantially flush therewith, said contactmember being so disposed that a first and second brush contact saidcontact member in the normal position of said carrier and that saidsecond and third brush contact said contact member in the actuatedposition of said carrier;

(1) three terminal lugs extending through said end plate;

and

(m) conductors connecting each terminal lug to one of said brushes sothat electric circuits connected to said terminal lugs can be opened andclosed upon actuation of said push button.

12. A snap action, push button switch comprising:

(a) a main housing of insulating material;

(b) an end plate closing one end of said housing;

(c) a push button extending through the opposite end of said housing andsubstantially closing said housing, said push button being slidable insaid housing from a normal to an actuated position and back again;

(d) a return spring disposed between said housing and said push buttonfor urging said push button into its normal position;

(e) a carrier of insulating material slidably disposed in said housingand forming substantially a triangular prism having three substantiallyfiat surfaces, said housing providing three spaced receptacles andhaving two spaced stop members, said carrier being movable between saidtwo stop members from a normal to an actuated position;

(f) a conductive brush in each of said receptacles, said receptaclesbeing so disposed that each brush is in contact with one of the flatsurfaces of said carrier;

(g) first spring means urging each of said brushes against its carriersurface;

(h) said carrier being provided with two cams disposed in a planeintersecting said push button, each of said cams having two inclinedsubstantially flat plane surfaces projecting toward said push button;

(i) two telescoping cam followers slidably disposed in said push buttonand movable therewith;

(j) second spring means for urging said cam followers away from eachother and against the inclined surfaces of said two cams, whereby upondepressing said push button said cam followers will ride over theinclined surfaces of said cams to force said carrier to move suddenly ina direction opposite the direction of movement of said push buttonagainst one of said stop members and to force said carrier to returnsuddenly into its normal position upon releasing said push button;

(k) a continuous conductive contact member extending over the fiatsurfaces of said carrier and substantially flush therewith, said contactmember being so disposed that a first and a second brush contact saidcontact member in the normal position of said carrier and that saidsecond and third brush contact said contact member in the actuatedposition of said carrier;

(1) three terminal lugs extending through said end plate;

(m) conductors connecting each terminal lug to one of said brushes sothat electric circuits connected to said terminal lugs can be opened andclosed upon actuation of said push button; and r (n) an insulatinglubricant having a high dielectric constant provided between saidbrushes and contact member for encapsulating and insulating from eachother particles worn off said brush and said contact member.

References Cited by the Examiner UNITED STATES PATENTS 994,493 6/11Altemus 200-77 2,910,552 10/59 Lindgren 200166 BERNARD A. GILHEANY,Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

1. A SNAP ACTION, PUSH BUTTON SWITCH COMPRISING: (A) A PUSH BUTTONADAPTED TO BE DEPRESSED FROM A NORMAL TO AN ACTUATED POSITION; (B) FIRSTSPRING MEANS URGING SAID PUSH BUTTON INTO ITS NORMAL POSITION; (C) CAMMEANS HAVING TWO CAM SURFACES FORMING AN EDGE PROJECTING TOWARD ANDDISPOSED ADJACENT SAID PUSH BOTTON, SAID CAM MEANS BEING MOVABLEINDEPENDENTLY OF THE MOVEMENT OF SAID PUSH BUTTON FROM A NORMAL TO ANACTUATED POSITION AND BACK AGAIN; (D) CAM FOLLOWER SLIDABLY DISPOSED INSAID PUSH BUTTON AND MOVABLE THEREWITH; (E) SECOND SPRING MEANS URGINGSAID CAM FOLLOWER AGAINST THE SURFACES OF SAID CAM MEANS, WHEREBY UPONDEPRESSING SAID PUSH BUTTON, SAID CAM FOLLOWER WILL RIDE OVER ONE OFSAID SURFACES TO FORCE SAID CAM MEANS TO MOVE SUDDENLY IN A DIRECTIONOPPOSITE THE DIRECTION OF MOVEMENT OF SAID PUSH BUTTON, AND WHEREBY SAIDCAM MEANS WILL RETURN SUDDENLY TO ITS ORIGINAL POSITION UPON RELEASE OFSAID PUSH BUTTON; (F) A MOVABLE CARRIER SECURED TO SAID CAM MEANS ANDMOVABLE THEREWITH; (G) TWO BRUSHES FIXEDLY DISPOSED ABOUT SAID CARRIERAND IN CONTACT THEREWITH AND; (H) A CONTACT MEMBER HAVING PORTIONSDISPOSED IN SAID CARRIER SO AS TO BE ENGAGEABLE WITH BOTH OF SAIDBRUSHES IN ONE POSITION OF SAID CARRIER AND AS TO BE DISSENGAGED FROM ATLEAST ONE OF SAID BRUSHES IN THE OTHER POSITION THEREOF.